1. Field of the Invention
The invention relates to a set of golf clubs. More particularly, the invention relates to a set of golf clubs employing a two-piece golf club shaft wherein the lengths of the first and second shaft members vary as the loft of the golf club varies.
2. Description of the Prior Art
Since golf clubs have been manufactured in sets, it has been an objective in the manufacture of golf clubs to achieve a degree of consistency such that variations between clubs occur within a predictable pattern. In the early days of golf, wooden shafts, most often made from hickory, were used for golf clubs. It was difficult to match a set of golf clubs with these wooden shafts. Occasionally players with an extraordinary feel could find a set of clubs that were fairly closely matched by individually testing each club until a proper feel was obtained.
With the advent of steel golf club shafts, wooden shafts became a thing of the past. Steel is isotropic in nature and, therefore, provides the mechanical consistency to enable a set of golf clubs to be closely matched in playability.
In recent years, golf club shafts have been made from carbon fiber composites, commonly known as graphite shafts. The graphite shafts have an increased strength to weight characteristic which allows a shaft, and ultimately a golf club, to be made lighter. In addition, graphite provides an increased vibration absorption capability, thereby creating a softer feel when a club impacts a golf ball. The ability of carbon fiber composite shafts to absorb vibrations generated upon striking a golf ball is not only favorable in improving the general feel of a golf club, but is immensely valuable to those suffering from various physical ailments, including, arthritis or tendinitis.
Graphite shafts are typically made by wrapping flags of resin pre-pregged carbon fiber on a mandrel and suitably curing the resin in an oven. Other graphite shafts are made by winding a pre-pregged carbon fiber tow on a mandrel and heating to cure the epoxy.
While carbon fiber composite shafts are generally lighter than prior steel shafts, they exhibit a variety of shortcomings. For example, carbon fiber shafts are commonly inconsistent in feel and mechanical properties. From a manufacturing perspective, it is very difficult and expensive to generate matched sets of golf clubs utilizing carbon fiber composite shafts. Currently there is no cost effective way to produce, in volume, shafts overcoming the shortcomings discussed above.
With this in mind, the manufacture of a set of consistently playable irons is very difficult where one wishes to utilize carbon fiber composite shafts. The relative mechanical inconsistency of the carbon fiber composite materials makes for a set of irons with widely varying playability. This inconsistency is highly undesirable where golfers wish to clearly utilize a set of interrelated golf clubs having the same feel and mechanical characteristics.
Attempts have been made in the past to create a two-piece composite golf shaft. For example U.S. Pat. No. 4,836,545 to Pompa, is directed to a two-piece composite golf shaft having a lower metallic tip section and an upper butt section made of a fiber resin composite or graphite, the term commonly used in the golf industry. The two sections are telescopically fit together and bonded. However, the two-piece composite golf shaft disclosed by Pompa fails to provide a golf shaft exhibiting the desired mechanical consistency, vibration, dampening, stabilization and flex varying characteristics desired by a wide range of golfers.
In addition, Pat Simmons attempted to develop a steel/graphite shaft in the mid 1970s. The shaft included an upper section composed of steel and a lower section composed of graphite. The lower section accounted for approximately 30% of the total length of the golf club shaft. Simmons"" shaft, however, failed to take advantage of the positive features of steel and graphite. Specifically, the length of the lower section maintained many of the negative features of graphite in the composite shaft, while providing a structure which readily broke under the force of striking a golf ball. In addition, the length of the lower section took away the bending and consistency provided by a standard steel shaft.
In developing the shaft described in the ""332 application it has been found that there is a tendency for longer, less lofted irons and woods to develop greater vibration, bending and torsion. This is primarily due to the increased forces which are applied to these golf clubs as they are swung; it being appreciated that the clubs are longer and, therefore, are swung in a greater arc with correspondingly greater centrifugal forces. Greater forces are also produced by these longer, lower loft clubs because of the tendency of the golfer to hit a golf ball farther and with a more aggressive swing. This is opposed to shorter clubs which generally are swung slower and with more finesse.
Furthermore, the longer golf clubs create a greater swing speed for a given force, which produces greater vibrational effects when a golf ball is struck. The vibrations are even more pronounced when the ball is not struck precisely on the center of percussion of a club head.
It will be appreciated that golf clubs made with a shaft having a standardized graphite section transfer more of the aforementioned undesirable characteristics to the golfer""s hands when longer clubs are used during the execution of a golf shot. As such, a need exists for a set of golf shafts compensating for the differing requirements of low lofted and high lofted golf clubs. The present invention provides such a set of golf clubs.
It is, therefore, an object of the present invention to provide a set of golf clubs employing a two-piece golf club shaft wherein the lengths of the first and second shaft members vary as the loft of the golf club varies. The set of clubs includes a plurality of golf clubs having varying lofts extending from lower loft golf clubs to higher loft golf clubs, wherein each golf club includes a club head and a shaft having a distal end and a butt. Each shaft includes a first member having a first end located at the butt end of the golf club shaft and a second end positioned slightly short of the distal end of the golf club shaft. A second member is secured to the second end of the first member. The second member extends from the second end of the first member to the distal end of the golf club shaft and includes a first end securely coupled to the second end of the first member and a second end which is ultimately secured to a golf club head. The second member progressively decreases in length as the plurality of golf clubs extend from the lower lofted golf clubs to the higher lofted golf clubs.
It is also an object of the present invention to provide a set of golf clubs wherein the first member is formed from a rigid material offering mechanical consistency and the second member is formed from a vibration absorbing material which absorbs undesirable vibrations resulting from an individual striking a golf ball.
It is a further object of the present invention to provide a set of golf clubs wherein the first member is formed from a rigid material offering mechanical consistency and the second member is formed from a material controlling the bending and torsional stiffness at the distal end of the golf club shaft upon striking a golf ball to thereby stabilize a golf club head secured to the distal end of the golf club shaft.
It is another object of the present invention to provide a set of golf clubs wherein the second member is formed from a synthetic chemical compound.
It is still another object of the present invention to provide a set of golf clubs wherein the second member is formed from a fiberglass reinforced resin.
It is yet a further object of the present invention to provide a set of golf clubs wherein the second member is formed from a carbon fiber reinforced resin.
It is also an object of the present invention to provide a set of golf clubs wherein the first member is formed from steel.
It is another object of the present invention to provide a set of golf clubs wherein the second member is approximately 6.25 inches in length for the lowest loft golf club and the second member is approximately 3 inches for the highest loft golf club.
It is a further object of the present invention to provide a set of golf clubs wherein the second member is a solid core construction.
It is also an object of the present invention to provide a set of golf clubs wherein said second member of each golf club shaft is progressively longer as the overall length of the golf club increases.
Other objects, advantages and salient features of the invention will become apparent from the following detailed description, which taken in conjunction with the annexed drawings, discloses a preferred, but non-limiting, embodiment of the subject invention.